Nicene and Ante-Nicene Fathers, Ser. II, Vol. XI:The Works of John Cassian.: Chapter XIX. That the birth of Christ in time diminished nothing of the glory and power of His Deity.

Chapter XIX.

That the birth of Christ in time diminished nothing of the glory and power of His Deity.

For the fact that He came of the flesh and in the flesh, has reference to His birth, and involves no diminution in Him: and He was simply born, not changed for the worse. 2572
For though, still remaining in the form of God, He took upon Him the form of a servant, yet the weakness of His human constitution had no effect on His nature as God: but while the power of His Deity remained whole and unimpaired, all that took place in His human flesh was an advancement of His manhood and no diminution of His glory. For when God was born in human flesh, He was not born in human flesh in such a way as not to remain p. 601Divine in Himself, but so that, while the Godhead remained as before, God might become man. And so Martha while she saw with her bodily eyes the man, confessed Him by spiritual sight to be God, saying, “Yea, Lord, I have believed that Thou art the Christ the Son of the living God, who art come into the world.” 2573
So Peter, owing to the Holy Spirits revelation, while externally he beheld the Son of man, yet proclaimed Him to be the Son of God, saying, “Thou art the Christ, the Son of the living God.” 2574
So Thomas when he touched the flesh, believed that he had touched God saying, “My Lord and my God.” 2575
For they all confessed but one Christ, so as not to make Him two. Do you therefore believe Him; and so believe that Jesus Christ the Lord of all, both only Begotten and first-born, is both Creator of all things and Preserver of men and that the same Person is first the framer of the whole world, and afterwards redeemer of mankind? Who still remaining with the Father and in the Father, Being of one substance with the Father, did (as the Apostle says), “Take the form of a servant, and humble Himself even unto death, the death of the Cross:” 2576
and (as the Creed says) “was born of the Virgin Mary, crucified under Pontius Pilate, and was buried. And the third day He rose again according to the Scriptures; and ascended into heaven; and shall come again to judge both the quick and the dead.” This is our faith; this is our salvation: to believe that our God and Lord Jesus Christ is one and the same before all things and after all things. For, as it is written, “Jesus Christ is yesterday and today and the same for ever.” 2577
For “yesterday” signifies all time past, wherein, before the beginning, He was begotten of the Father. “Today” covers the time of this world, in which He was again born of the Virgin, suffered, and rose again. But by the expression the same “for ever” is denoted the whole boundless eternity to come.